a nutritional journey to optimal bone health

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Archive | March 2012

Children don’t spend any time thinking about their bones. So here’s some news for those who care for children: Make sure they get enough vitamin D. A recent study published in the Archives of Pediatrics and Adolescent Medicine found that low vitamin D levels were associated with stress fractures.

The study followed 6,712 athletic girls aged nine to sixteen for seven years, monitoring dairy, calcium, and vitamin D intakes. Over the seven years, 3.9 % developed stress fractures. Those with the highest vitamin D intake, though, suffered the fewest fractures.

This agrees with the correlation that many researchers are finding between bone health and vitamin D levels, and points to the need to protect bones even in childhood.

I recently listened to a fascinating lecture by Dr. Stasha Gominak on vitamin D. She’s a neurologist who has identified a most interesting connection between low vitamin D levels and poor sleep quality. She makes so many fascinating comments on the subject that I recommend you listen to all four parts of the lecture. However, something she brought to my attention that particularly relates to this post about children is the extent to which our vitamin D intake from sun exposure (the optimum kind of D) has dropped in one generation.

When I was growing up in the 60s and 70s no one in my suburb had central air conditioning; we played outdoors, and when the house got really hot we even ate outside, with no gazebo. We hadn’t yet heard of sunscreen, so our skin was fully exposed to the sun. Kids walked or biked to their destinations, and we were free to wander the neighbourhood. Our favourite activities involved a lot of moving around, usually with others, especially since there was nothing to watch on TV for most of the day. At least for the summer, we got all the vitamin D we needed (as well as a good bit of bone-building exercise).

By contrast, when my children came along in the late 80s the house was pleasantly cooled, so they stayed indoors a whole lot more to keep comfortable. Whenever they were outside we made sure they were slathered in sunscreen, effectively preventing their skin from making that essential vitamin D. Furthermore, since the world had grown much more aware of predators and other nasties, we drove them around as much as we could. And by then VCRs and video games gave them a lot of indoor entertainment. All told, in the name of improving their lifestyle, we deprived them from what’s proving to be a vital vitamin in preventing a dizzying number of diseases.

My conclusion from reading about vitamin D? When possible I must get 15 minutes per day of sun exposure on bare skin, no sunscreen. If I had children now I’d make sure they did, too. The rest of the year, supplements are essential.

Now back to the study I mentioned above. To the surprise of researchers, those with the highest dairy and calcium intakes also suffered the most fractures:

“In contrast, there was no evidence that calcium and dairy intakes were protective against developing a stress fracture or that soda intake was predictive of an increased risk of stress fracture or confounded the association between dairy, calcium or vitamin D intakes and fracture risk,” the authors comment.

The authors also note that in a stratified analysis that high calcium intake was associated with a greater risk of developing a stress fracture, although they suggest that “unexpected finding” warrants more study.”

Yup, calcium is not the key bone-builder. Make sure you get your vitamin D.

My grandmother probably never heard of osteoporosis. For most of her life the disease was rare and largely unknown. But in 1982, right around her 90th birthday (and by then she was too old to care) the word osteoporosis was suddenly thrust into the common vocabulary. A massive public information campaign began, warning post-menopausal women by every means possible of imminent danger and disfigurement from weakened bones. The pharmaceutical companies, pushing their lucrative hormone replacement therapy (HRT), sponsored the campaign that sent a generation of fearful women scurrying to their doctors for prescriptions. No one seemed concerned about the absence of studies that proved HRT could prevent or reverse osteoporosis. Soon, though, a problem did emerge: there was no easy way to test the strength of bones in living people. So the Dual Energy X-ray Absorptiometry (DEXA) machine was developed in 1988, and finally our bones could all be compared on the basis of density.

Subsequently, the World Health Organization established a large database of DEXA readings, and in 1994 they announced international standards for osteoporosis. They also changed its definition. It went from being a disease characterized by fragility fractures to a condition marked by low bone mineral density, no fracture needed. Suddenly half of all post-menopausal women – and quite a few other people – were painted with the ominous diagnosis.

But the 1994 definition has some obvious shortcomings. It doesn’t take into account the fact that bone mineral density alone can not adequately predict the quality of our bones or their tensile strength which are most significant predictors of fractures. Also, the standards compare my bones with those of young women on a normal curve, not considering what might be normal and healthy and perfectly suitable for me. Furthermore, the DEXA machine that set the standards has some serious limitations, typically rating larger bones higher than smaller bones of the identical density. (There are more details here.) In other words, being diagnosed based solely on a DEXA score should not be nearly as scary as our doctors tell us.

Of course, fragility fractures truly are a serious problem, and I don’t want any. So I’m taking charge of all the factors that are within my control. I’m optimizing my nutrition and exercise, and minimizing the risk of falling. To reduce stress I’m turning back the clock on history, and living like my grandmother did, letting my bones do their work.

Aside from optimizing our nutrition through diet and supplements, the best gift we can give our bones is weight-bearing exercise. Study after study confirms that putting certain kinds of stresses on bones helps them to grow, or at least to resist shrinking.

So what exercise makes the difference for bones? Weight-bearing exercise includes almost any kind we do on our feet while working against gravity. Some examples are walking, jogging, hiking, dancing, and climbing stairs. Good news for me – gardening also counts! Swimming and biking are great for other reasons, but they are not weight-bearing because they don’t involve working our muscles and bones against gravity; therefore they aren’t the best for building bones.

If it were only as simple as going for a walk each day… But the problem is that our bones quickly adapt to the level of stress they usually encounter, then need new challenges to stimulate them to grow. So it helps to surprise them with new moves and greater intensities; for that reason it’s important to choose a variety of activities, and to alternate between lower and higher intensities. One study found that “inserting a 10-s rest interval between each load cycle amplifies bone’s response to mechanical loading”. That suggests that our bones are more stimulated to grow by a sequence of high intensity short bursts interspersed with 10-second rests, than by longer periods of sustained exercise. So digging the garden – as soon as I can get to it – will be better for my bones than a long run.

Exercise on our feet is vital for our vulnerable hip joints (femoral necks), as well as our spines and femurs. While those are the sites that the DEXA machines scan for density, we have other bones to consider: wrists and upper arms are also prone to fractures. So it makes sense to include a range of activities that stress those bones, like pushups, triceps dips, and carrying heavy groceries. Here’s a link to a site with lots of exercise suggestions.

Anything that improves our balance helps reduce the likelihood of falling. Lately I’ve opted to spend life’s less interesting moments standing on one foot, then switching to the other. It hasn’t taken long for me to develop impressive flamingo skills, which I practise while brushing my teeth, putting on socks, waiting in line, or talking on the phone. One day this should help me catch myself before falling.

But what about all the warnings for people with osteoporosis? “BE CAREFUL. Don’t run, or jump, or twist, or hug anyone, or sneeze.” Yes, if you have osteoporosis it’s essential that you exercise appropriately for your condition, and with medical approval. Consulting a qualified trainer is a good idea. These warnings are particularly important:

Do NOT do any high impact exercises without medical approval. These can result in stress fractures.

Do NOT do exercises that involve bending forward at the waist, such as toe-touching. These can result in spontaneous crush fractures of the spine when coming back up from this position.

Personally, I’ve been able to continue hugging and sneezing without breaking anything. I also run gently on a treadmill (lower impact than on the road), and I might have mentioned that I plan to garden…soon. For anyone concerned about bone density – find some activities you can fit into your day and DO THEM. Life as you know it may depend on it.